Recapture Heterogeneity in Cliff Swallows: Increased Exposure to Mist Nets Leads to Net Avoidance

Ecologists often use mark-recapture to estimate demographic variables such as abundance, growth rate, or survival for samples of wild animal populations. A common assumption underlying mark-recapture is that all animals have an equal probability of detection, and failure to meet or correct for this assumption–as when certain members of the population are either easier or more difficult to capture than other animals–can lead to biased and inaccurate demographic estimates. We built within-year and among-years Cormack-Jolly-Seber recaptures-only models to identify causes of capture heterogeneity for a population of colonially nesting cliff swallows (Petrochelidon pyrrhonota) caught using mist-netting as a part of a 20-year mark-recapture study in southwestern Nebraska, U.S.A. Daily detection of cliff swallows caught in stationary mist nets at their colony sites declined as the birds got older and as the frequency of netting at a site within a season increased. Experienced birds’ avoidance of the net could be countered by sudden disturbances that startled them into a net, such as when we dropped a net over the side of a bridge or flushed nesting cliff swallows into a stationary net positioned at a colony entrance. Our results support the widely held, but seldom tested, belief that birds learn to avoid stationary mist nets over time, but also show that modifications of traditional field methods can reduce this source of recapture heterogeneity.     

Reactive Oxygen Species Modulate the Barrier Function of the Human Glomerular Endothelial Glycocalyx

Reactive oxygen species (ROS) play a key role in the pathogenesis of proteinuria in glomerular diseases like diabetic nephropathy. Glomerular endothelial cell (GEnC) glycocalyx covers the luminal aspect of the glomerular capillary wall and makes an important contribution to the glomerular barrier. ROS are known to depolymerise glycosaminoglycan (GAG) chains of proteoglycans, which are crucial for the barrier function of GEnC glycocalyx. The aim of this study is to investigate the direct effects of ROS on the structure and function of GEnC glycocalyx using conditionally immortalised human GEnC. ROS were generated by exogenous hydrogen peroxide. Biosynthesis and cleavage of GAG chains was analyzed by radiolabelling (S³⁵ and ³H-glucosamine). GAG chains were quantified on GEnC surface and in the cell supernatant using liquid chromatography and immunofluorescence techniques. Barrier properties were estimated by measuring trans-endothelial passage of albumin. ROS caused a significant loss of WGA lectin and heparan sulphate staining from the surface of GEnC. This lead to an increase in trans-endothelial albumin passage. The latter could be inhibited by catalase and superoxide dismutase. The effect of ROS on GEnC was not mediated via the GAG biosynthetic pathway. Quantification of radiolabelled GAG fractions in the supernatant confirmed that ROS directly caused shedding of HS GAG. This finding is clinically relevant and suggests a mechanism by which ROS may cause proteinuria in clinical conditions associated with high oxidative stress.     

Oral but Not Intravenous Glucose Acutely Decreases Circulating Interleukin-6 Concentrations in Overweight Individuals

Background

Plasma interleukin-6 (IL-6) concentrations decrease acutely 1 h after ingestion of a glucose load or mixed meals and this may be mediated by an anti-inflammatory effect of insulin. The aim of the present study was to compare the effect of higher versus lower insulin levels on plasma IL-6 concentrations following oral compared with intravenous glucose administration in overweight/obese subjects.

Methods and Findings

Fifteen subjects (12 women and 3 men) with BMI >28 kg/m² were given an oral glucose load (75g) followed a week later by an intravenous infusion of glucose aimed at matching plasma glucose concentrations during the oral glucose load. A week later, they drank a volume of water equivalent to the volume consumed with the oral glucose load. Plasma glucose, insulin, nonesterified fatty acids, and IL-6 concentrations and blood hematocrit were measured at 30 minute intervals for 2 h following each intervention. Plasma IL-6 decreased (13–20%) significantly (P = 0.009) at 30 min to 90 min following the oral glucose load and did not change significantly following the other two interventions. The incremental area under the curve for plasma IL-6 concentrations following oral intake of glucose was significantly lower compared with concentrations following intravenous glucose (P = 0.005) and water control (P = 0.02). Circulating insulin concentrations were significantly (P<0.001) and 2.8 fold higher following oral compared with intravenous glucose administration.

Conclusions

These data show that plasma IL-6 concentrations did not decrease during isoglycemic, intravenous glucose administration suggesting that the markedly higher circulating insulin levels and/or gut-related factors may mediate the acute decrease in plasma IL-6 after oral glucose intake in overweight/obese subjects.

Trial Registration

Australian New Zealand Clinical Trials Registry ACTRN12612000491864     

Biochemical Analysis of the Plasmodium falciparum Erythrocyte-binding Antigen-175 (EBA175)-Glycophorin-A Interaction: IMPLICATIONS FOR VACCINE DESIGN*?

PfEBA175 has an important role in the invasion of human erythrocytes by Plasmodium falciparum and is therefore considered a high priority blood-stage malaria vaccine candidate. PfEBA175 mediates adhesion to erythrocytes through binding of the Duffy-binding-like (DBL) domains in its extracellular domain to Neu5Acα2–3Gal displayed on the O-linked glycans of glycophorin-A (GYPA). Because of the difficulties in expressing active full-length (FL) P. falciparum proteins in a recombinant form, previous analyses of the PfEBA175-GYPA interaction have largely focused on the DBL domains alone, and therefore they have not been performed in the context of the native protein sequence. Here, we express the entire ectodomain of PfEBA175 (PfEBA175 FL) in soluble form, allowing us to compare the biochemical and immunological properties with a fragment containing only the tandem DBL domains (“region II,” PfEBA175 RII). Recombinant PfEBA175 FL bound human erythrocytes in a trypsin and neuraminidase-sensitive manner and recognized Neu5Acα2–3Gal-containing glycans, confirming its biochemical activity. A quantitative binding analysis showed that PfEBA175 FL interacted with native GYPA with a K_D ∼0.26 μm and is capable of self-association. By comparison, the RII fragment alone bound GYPA with a lower affinity demonstrating that regions outside of the DBL domains are important for interactions with GYPA; antibodies directed to these other regions also contributed to the inhibition of parasite invasion. These data demonstrate the importance of PfEBA175 regions other than the DBL domains in the interaction with GYPA and merit their inclusion in an EBA175-based vaccine.     

Acclimation-induced changes in cell membrane composition and influence on cryotolerance of in vitro shoots of native plant species

Cell membranes are the primary sites of cryopreservation injury and measuring changes to membrane composition arising from cold acclimation may assist with providing a rationale for optimising cryopreservation methods. Shoot tips from two south-west Western Australian species, Grevillea scapigera and Loxocarya cinerea, and Arabidopsis thaliana (reference species) were subjected to cryopreservation using the droplet vitrification protocol. Two pre-conditioning regimes involving a constant temperature (23 °C, CT with a 12 h light/dark cycle) or an alternating temperature (AT) regime (20/10 °C with a 12 h light/dark cycle) were compared. Soluble sugars, sterols and phospholipids present in the shoot tips were analysed. Use of AT pre-conditioning (acclimation) resulted in a modest decrease in cryotolerance in A. thaliana, increased cryotolerance in G. scapigera, and increased survival in the non-frozen control explants of L. cinerea in comparison to CT pre-conditioning. Increased cryotolerance was accompanied by a higher total sugar sterol and phospholipid content, as well as an increase in strong hydrating phospholipid classes such as phosphatidylcholine. The double bond index of bound fatty acyl chains of phospholipids was greater after AT pre-conditioning, mostly due to a higher amount of monoenes in A. thaliana and trienes in G. scapigera and L. cinerea. These findings suggest that AT pre-conditioning treatments for in vitro plants can have a positive influence on cryotolerance for some plant species and this may be related to observed changes in the overall composition of cell membranes. However, alternative factors (e.g. oxidative stress) may be equally important with other species (e.g. L. cinerea).     

Status and population trends of Starling Sturnus vulgaris in Great Britain

Capsule Starling populations have declined markedly since 1964, with the greatest declines in pastoral areas in the south and west of Britain.

Aims To establish the size of the Starling population and its recent decline in different habitats and regions.

Methods We use distance-based transect sampling to establish, for the first time, robust estimates of population size in different habitats and regions. We then analyse long-term trend data from two extensive monitoring schemes using generalized additive models to find correlates of the population decline.

Results The mean national breeding population of Starling over the period 1994–2000 was estimated at about 8.5 million birds, with a 95% confidence interval of 8.1–10.8 million. Most Starlings (36%) occur in southern Britain and densities are greatest in suburban habitats. Populations in both suburban areas and the wider countryside declined by over 50% between 1964 and 2000, being greatest in the south and west of Britain and in areas of livestock farming.

Conclusions Changes in pastoral farming practices are likely to account for at least some of the decline in the wider countryside, probably related to changes in food resources, though these are largely unquantified.     

Evaluating Predictive Pharmacogenetic Signatures of Adverse Events in Colorectal Cancer Patients Treated with Fluoropyrimidines

The potential clinical utility of genetic markers associated with response to fluoropyrimidine treatment in colorectal cancer patients remains controversial despite extensive study. Our aim was to test the clinical validity of both novel and previously identified markers of adverse events in a broad clinical setting. We have conducted an observational pharmacogenetic study of early adverse events in a cohort study of 254 colorectal cancer patients treated with 5-fluorouracil or capecitabine. Sixteen variants of nine key folate (pharmacodynamic) and drug metabolising (pharmacokinetic) enzymes have been analysed as individual markers and/or signatures of markers. We found a significant association between TYMP S471L (rs11479) and early dose modifications and/or severe adverse events (adjusted OR = 2.02 [1.03; 4.00], p = 0.042, adjusted OR = 2.70 [1.23; 5.92], p = 0.01 respectively). There was also a significant association between these phenotypes and a signature of DPYD mutations (Adjusted OR = 3.96 [1.17; 13.33], p = 0.03, adjusted OR = 6.76 [1.99; 22.96], p = 0.002 respectively). We did not identify any significant associations between the individual candidate pharmacodynamic markers and toxicity. If a predictive test for early adverse events analysed the TYMP and DPYD variants as a signature, the sensitivity would be 45.5 %, with a positive predictive value of just 33.9 % and thus poor clinical validity. Most studies to date have been under-powered to consider multiple pharmacokinetic and pharmacodynamic variants simultaneously but this and similar individualised data sets could be pooled in meta-analyses to resolve uncertainties about the potential clinical utility of these markers.     

Resveratrol Induces Premature Senescence in Lung Cancer Cells via ROS-Mediated DNA Damage

Resveratrol (RV) is a natural component of red wine and grapes that has been shown to be a potential chemopreventive and anticancer agent. However, the molecular mechanisms underlying RV''s anticancer and chemopreventive effects are incompletely understood. Here we show that RV treatment inhibits the clonogenic growth of non-small cell lung cancer (NSCLC) cells in a dose-dependent manner. Interestingly, the tumor-suppressive effect of low dose RV was not associated with any significant changes in the expression of cleaved PARP and activated caspase-3, suggesting that low dose RV treatment may suppress tumor cell growth via an apoptosis-independent mechanism. Subsequent studies reveal that low dose RV treatment induces a significant increase in senescence-associated β–galactosidase (SA-β-gal) staining and elevated expression of p53 and p21 in NSCLC cells. Furthermore, we show that RV-induced suppression of lung cancer cell growth is associated with a decrease in the expression of EF1A. These results suggest that RV may exert its anticancer and chemopreventive effects through the induction of premature senescence. Mechanistically, RV-induced premature senescence correlates with increased DNA double strand breaks (DSBs) and reactive oxygen species (ROS) production in lung cancer cells. Inhibition of ROS production by N-acetylcysteine (NAC) attenuates RV-induced DNA DSBs and premature senescence. Furthermore, we show that RV treatment markedly induces NAPDH oxidase-5 (Nox5) expression in both A549 and H460 cells, suggesting that RV may increase ROS generation in lung cancer cells through upregulating Nox5 expression. Together, these findings demonstrate that low dose RV treatment inhibits lung cancer cell growth via a previously unappreciated mechanism, namely the induction of premature senescence through ROS-mediated DNA damage.     

Bringing Back a Healthy Buzz? Invertebrate Parasites and Reintroductions: A Case Study in Bumblebees

Reintroductions can play a key role in the conservation of endangered species. Parasites may impact reintroductions, both positively and negatively, but few case studies of how to manage parasites during reintroductions exist. Bumblebees are in decline at regional and global scales, and reintroductions can be used to re-establish extinct local populations. Here we report on how the risks associated with parasites are being managed in an ongoing reintroduction of the short-haired bumblebee, Bombus subterraneus, to the UK. Disease risk analysis was conducted and disease risk management plans constructed to design a capture-quarantine-release system that minimised the impacts on both the bumblebees and on their natural parasites. Given that bumblebee parasites are (i) generalists, (ii) geographically ubiquitous, and (iii) show evidence of local adaptation, the disease risk management plan was designed to limit the co-introduction of parasites from the source population in Sweden to the destination site in the UK. Results suggest that this process at best eliminated, or at least severely curtailed the co-introduction of parasites, and ongoing updates of the plan enabled minimization of impacts on natural host-parasite dynamics in the Swedish source population. This study suggests that methods designed for reintroductions of vertebrate species can be successfully applied to invertebrates. Future reintroductions of invertebrates where the parasite fauna is less well known should take advantage of next-generation barcoding and multiple survey years prior to the start of reintroductions, to develop comprehensive disease risk management plans.

     

Ontogeny and Sexual Dimorphism of <Emphasis Type="Italic">Glyptotherium texanum</Emphasis> (Xenarthra,Cingulata) from the Pliocene and Pleistocene (Blancan and Irvingtonian NALMA) of Arizona,New Mexico,and Mexico

North American glyptodonts originated from South American ancestors during the Great American Biotic Interchange no later than early Blancan North American Land Mammal Age (NALMA). A substantial expansion in population samples from the late Blancan 111 Ranch fauna of southeastern Arizona, several late Blancan faunas in New Mexico, and the early Blancan–Irvingtonian faunas of Guanajuato, Mexico, permit, analysis of sexual dimorphism and ontogeny of Glyptotherium texanum Osborn, 1903. Growth of carapacial osteoderms was allometric, including changes of the external sculpturing. Overall anatomy of the carapace changed with growth, with development of distinctive pre-iliac and post-iliac regions in lateral profile of adults. Skulls of adults possess a unique boss on the anterior surface of the descending process of the zygomatic arch that is not present in juveniles. Sexual dimorphism involves differences in anatomy of lateral and posterior osteoderms. Glyptotherium arizonae Gidley, 1926, is a junior synonym of G. texanum. The temporal distribution of G. texanum extends from early Blancan NALMA to Irvingtonian NALMA, with geographical distribution from Central America and Mexico to southern United States.